The present invention relates generally to protection devices for web press rotary equipment. More specifically, the present invention relates to a system and methodology for preventing wrap ups and damage to web press rotary equipment as a result of web breaks in the medium used in web printing or other rotary press.
In industrial process applications, particularly in automatic processes on web printing presses, maintaining continuity of the web is critical to proper operation of the web press rotary equipment. It is common for various web materials or medium (e.g., paper, textile, plastic, etc.) to be unwound and fed through a rotary process as part of an industrial operation (e.g., printing press, die cutter, perforating unit, gluing unit, coating unit, etc.). In some applications, a web printing press will utilize a rotary printing press that uses a continuous roll of paper that travels through the press.
In many of these industrial applications, the medium can tend to break when exiting from the rotary application due to, for example, a defect in the medium itself, or fatigue in the medium which may be caused by the industrial process. As press speeds increase, the need to protect the print unit from a potentially damaging web break also increases.
Breaks in the web medium can result from bad paper splices (splices are used when one roll is depleted and a new roll is started). Also, ineffective joints formed between the old paper rolls and new paper rolls, defective paper, and slime hole defects (a natural defect in the paper during the paper making process which leaves a hole in the paper which weakens the paper as it goes through the press) all contribute to breakage in the web medium.
Referring to FIG. 1, a schematic illustration of a web break is shown in a prior art rotary process without use of a web press rotary equipment protection device. In this figure, after a web medium 1 passes through a rotary process 2, and enters a dryer device 3, a web break 4 occurs. Therefore the continuity in the web medium 1 is disrupted.
As a result of the medium breaking after the rotary process, the medium will be pulled back into the last cylinders from which the web medium exited following the rotary process. This xe2x80x9cpull backxe2x80x9d causes xe2x80x9cwrap upsxe2x80x9d of the medium onto the rotary cylinders within the rotary process equipment. The result of wrap ups may include, among other things, damage to the rotary cylinder and cylinder journals. Additionally, other damage can be caused by the medium continuing to build up on the cylinders until the process is stopped by an operator or detection device. Further, damage that is caused to the rotary printing unit from a web wrap up after a web break can create the following problems for the printer: excessive down time caused by attempts to remove the paper from the cylinder; damage to rubber blankets associated with the printing apparatus; cylinder slippage resulting from printing cylinders that go out of time synchronization in relationship to other cylinders in the unit; and finally, bending of the printing cylinder journals. The removal and repair of cylinders increases down-time, labor costs, part costs and lost production.
FIG. 2 shows a schematic illustration of a resulting wrap up from the web break of FIG. 1. Web medium 1 following a break is shown wrapping up around a cylinder 5 of rotary process 2. The wrap up occurs because of the continued rotation of cylinder 5 in a direction indicated by arrow 6 even after the web medium 1 has been broken.
Also, a web press printing system will often include, in addition to one or more rotary printing operations, a final drying operation that dries the paper or other web medium that is fed through the web press. Web breaks that occur in or around the dryer can result in similar problems caused by the post-break medium entering the drying area.
In general, prior solutions included rollers that were constantly in motion that pushed the web onto a roller when a web break was detected.
In the past, high-speed web (paper) detection systems have been used to detect web breaks. These systems would monitor the status of the paper going through the press and determining if the paper was in tact or if it had broken. As a result of the web break being detected, the web detection system would send a signal to shut down the press and also to activate a severing device to cut the paper in a strategic location. These systems had limited success to catch each web break in time, particularly as press speeds increased.
Other systems, upon a break in the web, pulled paper out of the rotary application by two pinch rollers that would push the paper onto the floor causing clutter, and potentially unsafe conditions.
Therefore, it would be desirable to be able to, following a break in the web medium, prevent the web medium from being pulled back into a rotary process, and prevent xe2x80x9cwrap upsxe2x80x9d of the web medium onto the cylinders and journals used in the web process. Also, it would be desirable to retrieve the broken web medium from a dryer unit in the printing process.
Disclosed herein is a protection device for web press rotary equipment. In one aspect of the invention, a web press rotary equipment protection device for use with a rotary system and a web medium is disclosed, the device comprising: a roller having a web medium passage slot, the roller capable of receiving the web medium through the medium passage slot; wherein upon a break in the web medium, the roller rotates and engages the web medium in the medium passage slot such that the web medium wraps around the roller, thereby preventing the web medium from being pulled back into the rotary system.
In another aspect, a method of protecting a rotary web press disclosed, the method comprising: providing a roller having a web medium passage slot for receiving a web medium therethrough from the rotary web press; passing the web medium through the web medium passage slot of the roller.
Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings.